A matter of evolutionary life and death: an ecological model of growth and development in Homo erectus

Buckley, Carina A. (2005) A matter of evolutionary life and death: an ecological model of growth and development in Homo erectus.University of Southampton, School of Humanities,
Doctoral Thesis, 321pp.

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Description/Abstract

This thesis investigates the evolutionary ecology of Homo erectus, focussing on thedifferential impact of the environment on the species' life history strategy. Departingfrom previous studies in taking an integrated approach, it examines the related factors ofage-specific mortality, encephalisation, and the rate and energetic burden of growth, inorder to identify the mechanism by which H. erectus adapted to a diverse range ofclimates and environments, and how thoroughly that adaptation was achieved. Anexploration of the environmental tolerance of H erectus is framed within a model thatshows regions that comprised the core of the species, where tolerance is highest andconditions are optimum for growth and reproduction, and periphery regions which falltowards the extremes of tolerance and have repercussive effects on encephalisation,juvenile mortality and growth. Life history traits should vary accordingly, allowing thedevelopment of a model for the relationship between environmental variation and thedifferential evolution of H. erectus.

The work is organised thematically. Having provided an overview of evolutionaryecology and introduced the concept of paleo-demes as a means of organising, groupingand understanding the fossils of H. erectus, I address the shortcomings of the r-Kdichotomy with a study of age-specific mortality. This work is then applied to patterns ofencephalisation, and the energetic implications bf increasing brain size are addressed. Acomparative study of two modern human populations supports the prediction thatstability of environment translates into stability of growth, and these findings are appliedto H. erectus. I demonstrate that H erectus exhibited a long-term trend of an increasingcranial capacity, but that this was not uniform across the species and had varying success,with subsequent energetic stress in the young resulting in high juvenile mortality in someareas. I conclude that the model of core and periphery relates to the latitude of theenvironment, and that H. erectus was an adaptable and flexible species with a number ofstrategies available to maximise survival in a range of environmental conditions.